Supported by the Mount Everest Foundation, Ben Dare, Steven Fortune and Mike Rowe, forming the New Zealand Solu Khumbu Alpine Style Expedition, have climbed a probable new route to the crest of the North West Ridge of Kusum Kanguru (6,370m).
The three first hoped to make the first ascent of the North East Face of Kyajo Ri (6,186m), perhaps completing the line of the December 2009 Italian attempt, in which Enrico Bonino and Nicolas Meli reached a point on the unclimbed North Ridge c120m below the summit, after having overcome difficulties of M6+, WI5+ and A2 in the upper part of the face.
However, the New Zealanders were plagued by some of the worst spring weather this area of Nepal has experienced in recent years, and after attempts on both the North East Face and South West Ridge, they decided to retreat and focus their energies on Kusum Kanguru.
Although Kyajo Ri had almost certainly been climbed before 2002, in that year it was placed on the official 'trekking peak' list by the Nepalese Government, and had its first authorized ascent by Vincent Marche and Duncan Wilson. This pair reached the summit via the South West Ridge, today's popular Normal Route.
On arrival in base camp below Kusum Kanguru's virgin South West Face, the New Zealand team was initially greeted by conditions that, while a little thin, looked climbable.
This changed drastically, after several days of unseasonal heavy snowfall brought on an almost continuous series of avalanches, making the face infeasible to attempt safely.
They opted for a mixed rock rib well to the left, which they hoped to climb to the North West Ridge and then on to the summit.
Starting at about 4,500m, a long day took them to a bivouac at 5,300m, and the next day to the crest of the ridge at c5,500m, the team having overcome difficulties of M5. The weather and snow conditions were now bad, and realizing that continuing towards the summit was impractical, they started their descent.
Despite at least seven attempts from 1978 to 1980, during which Georges Bettembourg and Doug Scott, and later a team of Japanese, climbed to the lower North East Summit (6,350m) of Kusum Kanguru, the Main (South West) Top of this designated 'Trekking Peak' was not reached until the autumn of 1981.
In what is now acknowledged to be one of the most remarkable first ascents of lower Himalayan peaks, New Zealander Bill Denz made a solo traverse of the mountain in early October 1981.
Denz set up camp below the South West Face, the first person to visit this remote corner of the mountain, but in common with later parties was put off trying a direct line by falling ice.
Instead, he spent one and a half days climbing a mixed buttress on the left to the North West Ridge, where he bivouacked while waiting for the crest above to stabilize. He reached the Main Top the following day after a trying ascent, and bivouacked on the summit.
Next day he traversed the narrow connecting ridge to the North East Top, before descending the North West Flank and then spending a further two days bushwhacking to the standard Everest approach trail.
The only other route to the summit from this side of the mountain was climbed by Dick Renshaw and Stephen Venables in 1991. This pair also planned to try the South West Face, but finding it objectively dangerous, switched to the South West Buttress and upper South Ridge, a superb 1,250m route they completed in four days at TD+.
Since then several parties, including Americans and Slovenians have come to try the South West Face, yet none has managed to get established on this steep mixed wall of rock and ice.
The photograph shows the unclimbed South West Face of Kusum Kanguru. The Renshaw-Venables line follows the buttress on the right edge of the picture and then the skyline ridge to the main summit. The Denz and recent New Zealand lines are off picture to left.